ИСТИНА

Ascomycete fungus Podospora anserina is frequently used as a model organism in studies on the mechanisms of ageing. While P. anserina has a limited lifespan with clear signs of ageing when grown on solid media, it shows no evidence of senescence when cultured under aeration on liquid media. Apart from transition to unlimited growth, submerged cultivation triggers pronounced changes in mycelium morphology. To determine whether there might be a genetic basis for the observed phenotypic changes we conducted a long-term submerged cultivation experiment of 8 replicate lineages of P. anserina and analyzed genetic changes that arose and became fixed in the replicate lines during the course of the experiment. After 268 serial passages 8 replicate lines fixed a total of 129 point mutations, including 52 missense and 8 nonsense mutations. Numbers of both missense and nonsense variants were substantially higher than expected by chance. The observed enrichment of the fixed mutations for protein-altering variants suggests that some of the mutations might be adaptive. Functional annotation of the fixed mutations provides further evidence that some of them might result in the adaptive phenotype: several of the fixed variants affect genes involved in growth and development (pro1, FlbA, FadA). Moreover, we observe parallel evolution at the gene level with 4 genes possessing protein-altering mutations fixed in parallel in more than one independent lineage. This work was supported by the RFBR grant 16-04-01845а.